Abstract
OBJECTIVESAlthough smoking is associated with both low socioeconomic status and blood cadmium (Cd) levels, the association between socioeconomic status and Cd levels remains unclear. Therefore, our study aimed to examine this association and to clarify whether smoking is a confounding or mediating variable in this relationship.METHODSData (n=7,734) were drawn from the Korea National Health and Nutrition Examination Survey (KNHANES, 2008- 2011), including years that contained data on blood Cd and urinary cotinine levels. We investigated the associations of income, education, and occupation with blood Cd levels. Smoking was investigated by categorizing participants by smoking status (never, former, and current) and pack-years into quartiles. The weekly frequency of rice and barley intake was analyzed to gain insights into participants’ dietary patterns. Additionally, urinary cotinine levels were used to ensure the validity of the smoking variables.RESULTSParticipants earning a low income and with less formal education had higher blood Cd levels. After controlling for smoking, the association between income and Cd levels substantially weakened. Further controlling for education, the association between income and Cd levels disappeared. However, there was a strong negative association between education and Cd levels, even after controlling for smoking history, pack-years, and urinary cotinine levels.CONCLUSIONSIn cross-sectional data from the KNHANES, blood Cd levels were significantly higher among those with a low income and less formal education. Smoking history contributed to, but did not fully explain, these associations.
Highlights
Cadmium (Cd) is well known as a heavy metal used in our daily life, occupational and environmental exposure to which is harmful to the human body
Income did not show a significant association. In this analysis of cross-sectional data from the KNHANES, we aimed to explain the association between blood Cd levels and income using a modeling method in which factors related to Cd levels, such as sex, smoking status, education, and occupation, were added step by step
Blood Cd levels were significantly higher among those with low income and less formal education. These associations were substantially attenuated after controlling for smoking status, they still remained present
Summary
Cadmium (Cd) is well known as a heavy metal used in our daily life, occupational and environmental exposure to which is harmful to the human body. The routes through which humans are exposed to Cd are commonly categorized as occupational exposure and environmental exposure (non-occupational exposure). The occupational route involves exposure to Cd by the mining, production, and consumption of non-ferrous metal or plating, welding, the utilization of storage batteries and agricultural chemicals, and pesticide production [5]. Environmental exposure to Cd most often occurs through food intake such as meat, shellfish, vegetables, and any form of food whose packaging contains Cd; exposure to cigarette smoking and dust from polluted soil are routes of chronic exposure [6,7]. In Korea, smoking prevalence was extremely high in the 2000s. Rice consumption is considered to be a major factor associated with high Cd levels in Asian countries, including Korea [8]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
